Apparatus for reject jigging



Sept. 5,, 1950 M. LiNTZ APPARATUS FOR REJECT JIGGING 4 Sheets-Sheet 1 Filed June 1946 ll ll wH H INVENTOR. Mark Lin/ ATTORNEY Sept. 5 1950 M. LINTZ 2,521,537

APPARATUS FOR RE JECT JIGGING Filed June 4, 1946 4 Sheets-Sheet 2 F'IE E FIE E [/0 soon a V .70 (m d maiar/k/ "Mfepm/ IN V EN TOR. Mark 1/272; BY

Sept. 5, 1950 M. LENTZ APPARATUS FOR REJECT JIGGING 4 Sheets-Sheet 4 Filed June 4, 1946 F'lEEi E i INVENTOR M r i BY 8 L r773 AM? ATTOR Patented Sept. 5, 1950 UNITED STATES PATENT OFFICE APPARATUS FOR REJECT JIGGING Mark Lintz, San Francisco, Calif.

Application June 4, 1946, Serial No. 674,242

3 Claims.

lizing the differences in the abilities of the grains to penetrate a semi-stationary bed made up of particles of solid materials. Essentially, a jig is an open box having a closed bottom. In the box a relatively short ranged separating bed is formed by pulsatin water currents acting on a bed of solid particles. These currents may all be upward, all downward, or alternately upward and downward; if the last, they may have equal accelerations in velocity in both directions, but usually they do not. The velocity of the water currents is variable throughout each cycle,

A metallurgical jig usuallly comprises a box containing a screen section over which a prepared ore, fed in continuously at the feed end, is passed and is subject to the jigging motion produced by a pulsating water pressure produced by various mechanical means in the lower part of the box. In advancing through the pulsating water bed, the difierent components in the material fed stratify according to their respective specific gravities, the heavy stratum being below the lighter. The heavy fine material is allowed to fall through the screen into the lowermost part of the box which is called the hutch;

the material removed from the hutch is called the hutch product. On some materials, iron shot is placed on the screen bed to limit the hutch product to heavy particles. Many variations are utilized in industry in the jig screen bed, amplitude and frequency of the pulsations, etc.

The screen is seldom over mesh, and generally finer, down to around 16 mesh at which point the fineness of the screen begins to limit the transmission of pulsations of the water through the screen. A heavy material of larger particle size than the screen mesh to be removed from the ore must be removed from the bed by mechanical means. In earlier practice,

it was common to provide a jig with a large area bed and to operate until the heavy coarse concentrate accumulated. The machine was then shut down and the concentrate removed by hand. In the parlance of metallurgical operators, such units were called bull jigs. Later cups were placed along the side of the jig box in front of the discharge gates. This allowed the heavier solids, under the pulsating action of the jig, to discharge at the side of the jig from the lower part of the bed. Thus, the heavy mamaterial treated.

terial discharged as a cup product, while the lighter material discharged over the end of the box. This arrangement was fairly satisfactory when the concentration of the heavy strata material was relatively low. Even then, constant attention and skill was required to effect a good separation. However, as the concentration 01' the heavy material increased and larger quantities had to be drawn off the cups, the capacity of the unit decreased, the separation was not clean, and a limitation on the use of such jigs was soon reached. Usually when about 25% of. the feed is to be removed from the bed by means .of the side cups, the economy and elliciency of the operation makes it desirable to use other methods.

In many metallurgical and non-metallic operations, the problem of removal of a small percentage of a light weight material has been presented but has not been successfully accomplished heretofore in a jig. I have successfully devised various modifications of a standard commercial metallurgical jig enablin removal of the light material from the bulk of the ore or This modification of the standard commercial metallurgical jig and the operation of such a jig are described herein.

Those versed in metallurgical practices will usually class a metallurgical jig as a concentrating device and the work done in the present field of commercial metallurgical jigging as r the light strata. My arrangement may not necessarily replace the present equipment in concentrate jigging. Rather, it usefulness is to make jigging applicable to materials not heretofore successfully jigged, and to difierent metallurgical problems.

As one example of the utility of my new reject ji and jigging operation, I have successfully removed a light weight porous mineral, hydromagnesite, from a decomposed serpentine ore.

Still another example of application of my invention is on a lead-zinc ore. When the heavy 'In'ade more difiicult.

sulphide of lead, zinc and iron is concentrated by standard concentrate jigging, the recovery is not high. Much of the ore in the mill feed is usually barren of sulphide, consisting of gangue and vein wall rock of less specific gravity than the sulphide bearing vein material. With my process of reject jigging I remove some 15% of the mill ore feed as a light fraction which has very low mineral content. This reject is removed very economically from the crushed ore before this is passed to the ball mill for subsequent fine grinding and flotation. This new practice has the effect of raising the mill feed from 12 /2% lead to 14% lead. Heretofore, the only rejection of mill feed was by hand picking, a slow, tedious, expensive and haphazard operation. My invention not only makes jigging practical in new fields, but also provides a new tool to improve present metallurgical practices.

Still another application of my invention of reject jigging is to bene'fidia-te cement raw materials. When the "limestone contains seams and pockets of c'her-t (a form of silica), this can be rejected by jigging, thus increasing the average lime c'ontent oi the material treated.

This "invention also relates to the preparation of a-sized aggregate suitable for use in the manufacture of concrete and for like uses. As is well known, concrete is made up of aggregate, sand and cement. To insure that theconcrete has all the necessary physical characteristics it is essential that the uality of the components going into the concrete be carefully controlled. In case the aggregate, for example, contains unsound materials such as particles of clay, chalk, decomposed granite, micaceous material 'and othor components which are not of adequate strength, the final strength of the concrete will be adversely aitecte'd. insure elimination of those unsound materials, it is usual to tumble the aggregate in a trommel screen to break the unsound materials into particles which are then washed awayfi his practice is of questionable e'ffectiveness and feasibility. From the scrubber the material goes to sizing screens for the production of 1 plus 1", -1" plus plus 92;, etc., so grading and screening-depending on the size and number of sizes of aggregate "desired. Unsound material, previously reduced to fines, is rejected from the coarse product. However, in many instances, the objectionable material is strongenough to pass through the scrub- "her and appear in the coarse aggregate to later decompose by weathering in the aggregate stockpiles or in use in the concrete to the detriment of the concrete-duality.

Various other steps have been taken to insure provision of an aggregate free of 'such unsound materials. For example, in preparing the aggregate utilized in the Shasta Dam "in California,

"it was found necessary to install large ball mill type-scrubbers loaded with flat slugs to minimize the grinding of the-sand and still disintegrate the unsound material into fine particles. However, difficulty arose in that with the unsound 'material reduced to finely divided size, recovery of the fine sand present in the wash water was It was necessary to resort to sizing, hydro-separation and further washing.

These increased the cost of the aggregate.

I have 'found that it is possible to remove the objectionable unsound Cal 'as such freni a mass of proposed aggrega e and to accomplish this without any reduc on of the unsound material to finely divided form. This I accomplish by practicing upon the aggregate a reject jigging operation.

I have found that by feeding the raw aggregate feed to a suitable jig, preferably after the over-sized material has been removed, the unsound material is readily rejected, even generally before clay and chalk particles present become wet through by the water in the jig. This is a reversal of the usual jig action for instead of removing a small fraction of a 'heavy component, I remove a small fraction of a light and worthless component. In an acceptable aggregate feed, the

"unsound component present may be relatively small, of the 'order of 5% and less. However, I have found that the light fraction, even though present in only a relatively small amount, is readily removed. With this beneficiation step, I materially improve the sand and aggregate for the purpose of making concrete. This also makes available sound sand and aggregate from sources heretofore considered ns'aunsuitable. ln using my method of Reject digging, II also improve and simplify the usual washing operations. The .proc- -ess of this invention enables san'd'and gravel to be produced from "sources heretofore considered unsuited as we'llas tromapprove'd and acceptable sources.

Another object of the invention is to provide an improved jig.

In the drawings accompanying :and forming a part hereof:

Figure 1 is a side elevation partly in section through a suitable .vjig which can be employed to practice the invention.

Figure 2 is aplan view of 'a'portionof the control mechanism utilized on the jig.

Figure 3 is a front elevation *of the discharge 'end of the jig.

Figure 4 is a section taken along the :line 4- 4 in Figure 1.

Figure 5 is adiagram of a flow'sheet and apparatus utilized to practice the invention-asinprep- Iarati'on of a concrete aggregate.

Figure '6 is a diagram of a flow sheet and apparatus utilized to practice the invention on an'ore.

Figure 7 is a fragmentary side elevation of a modified form of jig.

Figure 8 is a planview of amocl'rfied form of jig taken along line =8-B in Figure '7.

Figure :9 is a fragmentary section through the 'side of thejig'along line 99 in Figure 8.

The invention will be first described as practiced'and applied to manufacture of an aggregate.

Referring to Figure 5 of the drawing, the crushed rock or the .gravel and sand .plant .feed to be utilized as the sound aggregate source is fed to a suitable screening device. Water is preferably added to the screen to assist in sizing the material, the over-sized being removed and sent to a crusher for the over-sized material which, after crushing, is returned. The screened material, tree of over-sized material, is then sent to a suitable jig or to a battery of jigs, wash water being introduced into the ,jigs.

One can utilize any suitable ,jig equipped for removal 'of the light material as a separate vfraction andI have successfully utilized that which is presently described. The unsound material, the chalk, decomposed granite, twigs, leaves, roots, micace'ouS material and all light material, readily floats on and is removed, preferably ahead of the usual .jig end gate while the sand is taken off as bottom fraction usually through that portion of the jig known as the hutch.

The clean material, the acceptable aggregate fraction, is taken off over the end of the jig. This material is useful as such, but I prefer to size the material and to store it in different bins according to the sizing effected as by passing it over suitable screens.

The sand fraction taken off and the sand recovered from the aggregate screening operation are preferably mixed and sized on suitable fine screens wherein the sand product is separated from the water by any suitable equipment and sent to a sand bin. The water from the screen, containing a small amount of sand, is subject to a classification to eliminate the fine sand component present which is sent to a sand bin.

If the clay present is fairly dry it will usually be reduced to a coarse size and when in the jig, will be rejected quickly, usually before the clay particles are wet through. The action of the jig also cleans off the solid aggregate particles and forces clay particles and fines upward for removal as a light fraction so the material passing over the jig end gates is remarkably free from clay.

As a jig one can use any suitable mechanism wherein the light unsound fraction can be taken off in substantially its original condition. The jig which I have used is shown in Figures 1-4.

Referring to the jig mechanism there shown, the jig includes a suitable box if mounted upon a supporting framework 8, the box being open at the top. A partition e is provided centrally of the box and divides the box into two compartments; a jig with any number of compartments can be used as desired. Transverse jig screens ii and I: are provided in the respective compartments and are provided with vertical transverse plates l4. A conical structure it depends beneath each screen to collect material passing the screen. A flexible shoe ii is secured to the exterior of each conical structure it and each shoe is mounted upon a pulsating cone l8.

Each pulsating cone is mounted upon trunnions l9 and bearings 25 on a walking beam 22 frame structure, the latter being supported by bearings 23 on cross shaft '24 supported on the frame 8. The walking beam. is oscillated by a pitma 26 carrying a bearing 2? engaged with an eccentric 28 on rotatable shaft 29, one end of the pitman being engaged with a cross shaft 3i on an end of the walking beam frame. The shaft 29 is rotated by suitable means (not shown) the shaft being mounted on suitable bearings 32. Each pulsating cone is provided with avalve body 34, a valve member 35 being positioned over each valve to permit sand collecting in the valve and in the pulsating cone to be removed as the hutch. Water or other suitable fluid is supplied through line into the upper portion of the cone to provide and maintain the requisite fluid body in the jig.

Means are provided for removing from the box I the light, unsound materials present in the aggregate. This means comprises one or more V-plates ll extended transversely across the box and depending into the box to leave a space between the bottom of the plate and the box. The point of the V extends upstream so that light material, passing through the box, is diverted out to the sides of the box. An opening 43 is provided just ahead of each end of each V-plate to permit removal of the light unsound material over adjustable gates 43 provided on each side of the box. In the drawings I have shown only one V-plate for convenience but, if desired, several V-plates 4! can be provided facing upstream and positioned to divert the light, unsound material to 6 suitable openings in the side of the box through which it is removed. a

Means are provided for coordinating the quantity of material present in the'box with the position of the discharge member or gate 5| over which the acceptable aggregate is passed. To accomplish this, a framework indicated generally at 52 is mounted upon the box 1 and upon this framework 52, at opposite ends, are mounted the cylinder and piston structures generally indicated at 53, adjustable rods 54 extending from the piston (the piston being included in the cylinder structure and not being shown). A fluid line 56 and 51 connects each of the cylinders to a control mechanism generally indicated by 58 and to which fluid is exhausted through line 630.

To coordinate the position of the discharge member 5| the level of material in the box'l, float 6! is provided, this being of such a size and configuration that it rides on top of the body of material in the box I. The float is retained in position by two rods 62 and 83, the rods being slidably mounted in suitable bearings 64 on a fixed plate 56. A spring 61 is mounted between a nut 68 on rod 63 and one of the bearings 64 to counter-balance a substantial portion of the load otherwise placed on the float and the weight of the float so that the float rides on the surface of the aggregate in the box.

Because of the pulsating and Wave-like movement of the material in the jig box, a lost motion connection is provided between rod 64 and the control mechanism 58. This lost motion connection is provided by threading rod 64 as at H and providing a pair of spaced nuts 72 thereon. A follower I3 is loosely mounted on the rod 84 and is adapted to be engaged and moved by the nuts 12. The follower 13 is oscillatably supported at one end of lever '14 which is mounted on a control member 56 extending into the control device 58. The other end of lever 74 carries a friction member Tl engaged with a friction element 18 so that the lever M is moved only by application of a force in excess of a, predetermined extent. The control device 58 is such that upon rotation of member 16, fluid is either furnished to or is released from the cylinder 53, and the gate 5! follows the level of the aggregate and is always in a predetermined relationship to the aggregate level. The control device -8 is of a well-known type.

In operation, washed, sized raw aggregate is fed the jig at one end of the box. It rapidly stratifies, as is indicated more or less diagrammatically in Figure 1, the light, unsound material rising to the surface while the sand passes through to the screens. The sand-free, sound aggregate passes under the V-plate and over the gate 5i to be recovered as the acceptable aggregate product ready f or final screening.

While I have described the production of an aggregate and sand for concrete manufacture, the invention is not limited in application to these. Another example of the utility of my process of reject jigging is illustrated in recovering a light weight porous mineral, hydrornagnesite, from a gangue material consisting of a decomposed Andcsitic material. Attempts to beneficiate this ore with a conventional concentrate jig were quite impractical in results, but utilizing the jig shown and by utilizing my method of reject jigging, I removed the nodules of light weight hydromagnesite very effectively.

Still another example of the utility of my process of reject jigging is the beneficiatlon of limestone containing veins and pockets of the 7 mineral chert for a raw material in the manufacture of cement. silica; its presence in excess in the limestone made the limestone unacceptable for cement manufacture. The chert had a specific gravity of 2-.46; the limestone, a specific gravity of 2.71. Bycrushing the. limestone containing the chert to sizes suitable as a feed to the jig heretofore described, the chert may be rejected from the limestone, the equipment being quite selective even with this small difference in specific gravity. For instance, a cement limestone raw material containin 72% CaCOs, whenv cleaned of chert by my method of reject jigging, was brought up to 84.3% (22.003. Another batch of the same raw material assaying 77.2% CaCOs when cleaned by my method of reject jigging was brought up to 86% CaCOa. Part of the benefieiation was through removal of clay and dirt as well as the chert reject, as both undesirable components are removed by my method. This development is particularly opportune in making available large tonnages of limestone which have an unacceptable initial composition.

A desirable size to feed to my present jig is -1 or 1 crushed rock. The preparation of the rock to this size is a small part of the overall crushing and grinding cost. The cost of my reject jigging operation is low in equipment installation cost and power requirements are insignificant in a cement mill circuit. I also wish to point out that the'silicious reject can in many cases be reclaimed to make the silicious component of the raw material mix, thus efiecting ideal plant control. At present some limestone and cement raw materials are being corrected in several instances by flotation. To accomplish this, the material must be ground in. ball mills to a fine mesh. As the fine grinding is expensive due to the high power costs while flotation is inherently inefiicient, correction of the composition of the raw material fed by my method is only a fraction of the cost of flotation.

Still another example of the utility of my method of reject jigging is illustrated in the beneficiation of a lead-zinc sulphide ore from a Nevada. mine. The ore is a heavy sulphide of lead, zinc, iron and copper with some-gold and silver values. The gangue is a comparative light specific gravity andesitic rock, mostly vein wall material. This problem illustrates the relation of the present concentrate jigging practice to my new method of rejectjigging. The ore from this deposit was concentrated during the recentwar emergency by crushing to size and concentrating into two Bendalari double cell jigs. The recovery of lead was fair, the recovery of zinc was poor. On large scale tests on this material with my new reject jigging method, utilizing the flow-sheet and the operations shown in Figure 6, I. am able to reject this gangue material from the bulk of the sulphide ore as a reject having very small sulphide content, probably lower in value than the flotation tails will be. On one batch assaying 12.5% lead, I reject of the jig feed as a light weight low value reject which brought up the treated ore to 14.6% lead.

On another batch assaying 4.6% lead, I rejected 24% of the jig feed as a light weight low value reject, which brought up the treated ore to 5.96% lead.

On another batch assaying 7.6% lead, I rejected 4% of the material as a light weight, low value reject, which brought up the treated ore to 7.86% lead.

This chert contained 74% The value of my method in this circuit is more than in the terms of assays value as it eliminates directly grinding and treating most of the waste rock, thus making the mill available to grind and treat the higher grade material, thus materially increasing production from the same equipment.

This is a new step in ore dressing practice. Heretofore, the only practice of rejecting barren rock from the mill feed consisted in hand picking the coarse rock, but with my method of reject jigging, the rejection of barren rock from a heavy ore mineral becomes a low cost high capacity step in the ore dressing procedure.

Certain refinements in the installation. and operation are sometimes necessary. The selection in the mechanical operation of the equipment is, relative; that is, if the jig feed is practically all sulphide heavy material, then the rejects. may contain values too high for rejection. Usual mine run ore will vary from all sulphide to sulphide containing considerable waste. For periods when no waste or very little reject material is present in the feed, I provide a waste or reject bin (Figure 6) in closed circuit with the reject from the jig, and a manual or automatic control to feed the waste into the jig feed. This provides a lightweight waste strate on the jig bed of substantially constant volume. This ensures, that the values will be depressed into the discharge at the end of the jig and will not rise and be taken off as a reject.

In the form of improved jig shown in, Figures 1 through 4, I have shown a jig in which only a single bafiie 4| is provided, the jig proper being provided with two openings or discharge gates 43, one upon each side of the jig box. Upon some materials, the utilization of a multiple baffle and discharge arrangement is of advantage. For example, such an arrangement enables various fractions to be removed selectively, such as a barren reject fraction, a middling fraction and a concentrate. This mode of operation has not heretofore been possible with a jig or in jigging practice. The number of baffles and discharge gates can be increased and made so effective that the quantity of material discharged over the end gate is relatively small, representing a concentrate. Utilizing multiple baffles and discharge gates enables jig having a longer bed to be utilized successfully and to perform operations heretofore impractical with previously known jigs.

In Figures 7, 8 and 9 I have illustrated a structure in which a first baffle 8| and a second bafile 82 are provided, the fiow being toward bafile 8i and thence on toward bafile 82. These baffles are generally similar in form to bafile 41. Material swept off the upper surface of the bed of material passing through the jig is discharged by baiile 8| through suitable openings either in the side of the jig box or in adjustable discharge ates 9.6, these openings being indicated at 83. Similarly bafiie 82- discharges material through a suitable opening in the side of the jig box or in the adjustable discharge gates 96. The openings 83, as appear in- Figure '7, preferably slope upwardly inthe direction of. advance of the material through the jig.

Referring further to Figures '7, 8 and 9, the provision of a bafile across the surface of the jig bed provides more or less of a dead drag upon the material and some mixing of the reject material with the valuable material may occur. In other words, the heme will. tend to scrape or plow the surface of the bed whereby the several different levers are mixed together. To decrease the extent of this and to facilitate discharge of the fraction or fractions desired, I have found it advantageous to apply a high frequency vibration to the baffle and to discharge gates positioned over the openings. This vibration can be of any desired order but I have successfully used vibratory rates between 1000 and 3600 cycles per minute.

One successful embodiment of a jig as generally described is shown in Figures 7, 8 and 9. As appears in Figure '7, plates 86 are mounted on the side of the jig I over each opening 33. Adjacent each slidable discharge gate 945 and on the upstream side thereof, a plate 87 is mounted upon the side of the box to extend beyond the adjacent portion of box 1 defining the opening through which the material is discharged. A spacer plate 84 is mounted on the downstream side of each opening; on this plate is positioned a rubber spacer sheet 98 supported by a plate 94. On the outside of the box and adjacent each opening is positioned a receptacle 38 carrying on each side thereof an angle iron 89. To provide a seal about the upstream side of the discharge gate 96, against one face of the angle iron 89 is positioned a metal spacer plate 9| while adjacent the outer edge of this same face of the angle iron is positioned a rubber sealing strip 92 in engagement with the outside face of the slidable gate. A rubber sealing strip 915 is also positioned between the spacer 9! to extend outwardly beyond the edge of the adjacent plate 81 and provided a seal between the inside surface of the slidable discharge gate 96 and seal the same effectively against liquid loss. On the downstream side of each gate, the rubber strip 93 abuts against a portion 91 of bafile 8| or baffle 82 to provide a seal on one side of the bafile. On the other side of the baflle, portion 91 is engaged with the rubber facing strip 98 which is positioned between plate 84 and the plate 94.

The position of each baflle and the discharge gates with respect to (1) the bed in the jig and (2) to one another can be suitably adjusted. To permit of this, plate I! is attached to the end of the discharge gate 96 and is suspended from plate 86 by the several threaded rods I03 and nuts H14. A vertical plate I06 is secured to each baffle as at I01, the plate including a horizontal portion I08 upon which is mounted a suitable vibrating device I09. This can be operated by application of air or electrically operated to impart the requisite degree of vibration to the bafile and to the discharge gates.

The position of the baffle with respect to the discharge gate and to the height of material in the bed is adjusted by means of threaded rod 1 l2 and nut I I3, the rod extending through plate HH and being engaged with a bracket I M which bears against the side of discharge plate 96 and carries several studs H6 extending through slots I I! in each discharge gate.

I claim:

1. In a jig, a jig box, means for pulsating a bed of material in said box, means for admitting material into said box at one end thereof, a gate at the other end thereof over which passes a material fraction issuing from the jig box, an opening in the side of the box, a baffle extending across the jig ahead of the opening for diverting and skimming oif the surface material on said bed ahead of said bafiie, and means for vibrating said baflie.

2. In a jig, a jig box, means for pulsating a bed of material in said box, means for admitting material into said box at one end thereof, a gate at the other end thereof over which passes a material fraction issuing from the jig box, a plurality of spaced openings along at least one side of the box, a baiile extending across the jig ahead of each opening for diverting and skimming off the surface material on said bed ahead of each of said bafiies, and means for vibrating each of said baflles.

3. In a jig, a jig box, means for pulsating a bed of material in said box, means for admitting material into said box at one end thereof, a gate at the other end thereof over which passes a material fraction issuing from the jig box, a p1u rality of spaced openings along at least one side of the box, a plate for controlling the size of each opening, a baffle extendin across the jig ahead of each opening for diverting and skimming oif the surface material on said bed ahead of each of said baflies, and means for vibrating each baflle and plate.

MARK LINTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,723,372 Reid Aug. 6, 1929 2,083,393 Norton June 8, 1937 2,309,275 Remer Jan. 26, 1943 2,421,576 Norton June 3, 194"! FOREIGN PATENTS Number Country Date 2,907 Great Britain of 1907 OTHER REFERENCES Chapman and Mott: Cleaning of Coal; London, 1928, pages 146, 158 to 160..

Rock Products: Jan, 1940; pages 27 and 28. 

